Telephone system



Jan. 8, 1929.

C. E; LOMAX TELEPHONE SYSTEM Original Filed Nov. 15. 21 3 Sheets-Sheet 1 Ilaranca ELmmsx HIT y:

Jan. 8, 1929.

C. E. LOMAX TELEPHONE; SYSTEM Original Filed Nov. 15. 1 21 Zwphsets-Sheet 2 Inusn ur u M m Ila arms ELnmax %ifin Jan. 8, 1929.

C. E. LOMAX TELEPHONE SYSTEM Original Filed Nov. 15. 1921 3 Sheets-Sheet 3 Inuen ur- Clarence Elm-max,

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Patented Jan. 8, 1929.

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CLARENCE E. LOMAX, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS,

TO AUTOMATIC ELECTRIC IN 0., OF CHICAGO, ILLINOIS, A CORPORATION OF DELA- WARE.

TELEPHONE SYSTEM.

Application filed. November 15, 1921, Serial No. 515,287. Renewed. May 7, 1926. I

The present invention relates to telephone systems in general, but is concernedmore particularly with telephone systems comprising both manual and automatic exchanges; and the principal object, briefly stated, is the production of new and improved circuit arrangements whereby the operation of the apparatus employed whenever a connection is set up from amanual to. an automatic exchange is improved so as to make it more satisfactory and desirable.

A special object is to provide circuit arrangements such that a B operator is given a flash recall when a trunk leading to her position is taken for use a second time before the first connection has been taken Other objects, which have to do with the carrying out of the general scheme and which will not be mentioned specifically at this time, will be explained fully hereinafter, reference being had to the accompany ng drawings comprising Figs. 13, lnclusive, which when arranged in order with the corresponding lines at the ends thereof in alignment show all the apparatus necessary for a complete connection between a calling substation A in themanual exchange and a called substation A in the automatic exchange.

The apparatus shown in Fig. 1 is assumed to be located in the manual exchange while the apparatus shown in Figs. 2 and 3 1s assumed to belocated in the automatic exchange, although if desired the apparatus shown in Fig. 2 may be located in the manual exchange also.

The substation A is an ordinary manual substation and is connected with the central exchange by means of the two conductors 11 and 12 as shown,

The A operators cord circuit 0 is of a well-known type and in the'prcsent instance is used to connect the calling line with a trunk leading to the exchange in which the called line terminates. e

The operators plug ending trunk circuit 0, Fig. 2, is permanently associated with the selector D by means of the conductors 66 and 67, as shown, and is used to connect the selector Dwith one of a plurality of trunk lines of which the trunk line comprising conductors 22 and 23 is one. This trunk circuit is shown complete and will be explained fully hereinafter.

The selector D, Fig. 3', as well as the con nector H, is an automatic switch of the wellknown vertical and rotary type and accordingly has its bank contacts arranged in horizontal rows or levels. The'circuits of these switches are not novel and since they are well known they need not be described. It will sutfice to say that these switchesare operated according to the well-known twowire system of control. of the connector H have been omitted for the sake of simplicity, only the line, release, and back bridge relays being shown.

' The line switch C in which line of the automatic substation A terminates is of the well-known rotary type in which the wipers haveno normal position and move in a forward direction only. The circuits of this switch alsoare well known and consequently need no description.

The apparatus, having been described in general, will now be described in connection with 'a more or less detailed description of" its operation. For this purpose it will be assumed that the subscriber at substation A in the manual exchange desires to obtain con- Most of the circuits nection with the subscriber at substation A ing, closes a circuit for the line lamp L at armature 17 whereupon the'said lamp L- becomes lighted. The operator, upon not-. ing the lighted condition of the lamp L, I inserts the answering plug of an idle cord circuit'into the jack J, the plug P of the cord circuit 0 for example. When this is done, cut-ofi relay 14: energizes in series with the lamp L and disconnects line relay 13 at armature 15, and removes ground from c01 ductor;12 at armature 16, whereupon line relay18 deenergizes, thereby extinguishing the lamp L. Supervisory relay 17 upon energizing over the calling subscribers loop, places a shunt around the supervisory amp- V L, thereby preventing the said lamp from w becoming lighted at this time.

The operator now throws the key K, which is a combined listening and ringing key, into listening position thereby connecting up the leads associated with her head set. She now converses with the calling subscriber and after ascertaining the exchange in which the line of the desired subscriber terminates, she

restores the key K to normal and inserts the plug P into a jack which we shall assume is the jack J the associated trunk being idle as indicated by the unlighted condition of the lamp L When the plug P is inserted intothe jack 7 J sleeve relay 21 energizes in series with the supervisory lamp L and the said lamp L becomes lighted. Upon energizing, relay 21 closes a circuit for the busy lamps L and L whereupon the'said lamps become lighted. o r

In the automatic exchange, the high resistance line relay 30, upon energizing over the loop comprising trunk conductors 22 and 23 and the calling end of the cord cirr cuit O, closes a circuit for the line lamp L whereupon the said lamp becomes lighted. Supervisory relay l8 inthe cord circuit 0, however, does not energize at this time owing to the high resistance of line -relay 30.

The B operator, upon noting the lighted condition of the line lamp L inserts a plug associated with an idle trunk circuit into the jack J the plug P associated with the trunk circuit 0 for example. When the plug P is inserted into the jack J line relay 30 is disconnected and, upon becoming deenergized, extinguishes the line lamp L As a further result of the plug P being inserted into the jack J the upper and lower left hand windings of the repeating coil associated with the plug P and the high resistance relay31 are bridged across the conductors 22 and 23 in series. Supervisory relay 18 of the cord circuit 0 does not energize at of the key K and its resting contact, and

. lighted.

armature 44 of relay 34and its resting contact. Thesupervisory lamp Ll now becomes The B operator now throws her key K, which is a combined calling device and listening key, into listening position, thereby connecting up the conductors associated with her head set at springs '61 and 62. She now converses with the calling subscriber and,

after having been apprised of the number of the desired subscribers' line, she throws the key K to the opposite or calling position, thereby closing a circuit for the connecting relay 36 at spring 63. Connecting relay 36, upon energizing, closes a locking circuit for itself at armature 48, which circuit includes armature 37 of relay 31 and its working contact. As a further result of the energization of connecting relay 36, it

connects up a bridge, including the upper and lower right hand windings of the associated repeating coil and the polarized relay 32, to the springs of the key K at armatures 47 and 49. As a still further re sult of the operation of'the kev K, abridge, including conductors and 71, contacts 68 of the release push button B, the impulse springs of the calling device S, and the secondary windings of the operators induction coil, is placed across trunk conductors66 and 67 at springs 64 and 65, and the said conductors 66 and 67 are disconnected from the working cont-acts of armatures 47 and 49.

In response to the placing of this bridge across the conductors 66 and 67, the line and release relays and 7 6 of the selector D energize, thereby preparing the switch for operation in the usual manner.

The operator now manipulates the calling device S in accordance with the digits of the desired number, whereupon the selector D is operated in the usual manner to extend the connection to the connector H, and the connector H is operated in the usual manner to finally c'onnect with the called line. After the connection is completed, ringing current is sent out intermittently from the connector H in any well known or approved manner to ring the bridged bell at the called substation.

The operator, having finished dialling the desired number, now restores the key K to normal position, thereby opening the intial circuit of connecting relay 36 at spring 63, and at the springs 64 and 65 shifting the bridge across conductors 66 and 67 so as to include the right hand windings of the associated repeating coil and polarized relay 32 instead of the bridge which includes the impulse springs of the calling device S. The automatic switches are now held up over the bridge including polarized relay 32, but thearmature 39 of the said relay is not operated owing to the fact that the current is flowing in a direction opposite to that in which it must flow in order to operate the said armature. When the subscriber at substation A responds to the ringing of his bell by removing his receiver, certain operations take place in the connector H with'the result that ringing current is removed from the called line and the called line is connected up to the upper and lower windings of back bridge relay 77. Back bridge relay 77, upon energizing over the called subscrihers loop, reverses the incoming trunk conductors as regards their connection with the upper and lower windings of line relay 78, whereupon the polarized relay 32 in the trunk circuit 0 responds by operating its armature 39, thereby closing a circuit for relay 33. Relay 33, upon energizing, closes a circuit for relay 34 at armature 42. Relay 34, upon energizing, extinguishes the lampL and closes a locking circuit for itself at armature 44, thereby giving the B operator answering supervision. As a further result of the energization of relay 33, it places a shunt arounda portion of the winding of relay 31, thereby lowering the resistance of the said relay sufl'iciently to allow supervisory relay-18 of the cord circuit 0 to energize. Upon energizing, supervisory relay 18' places a shunt around supervisory, lamp L whereupon the said lamp becomes extinguished togive the A operator answering supervision.

The calling and called subscribers may now converse with each other in the usual manner, the talking circuits being outlined by the heavy conductors. After the conversation is finished the tw subscribers replace their receivers; When the receiver is replaced at the substation A the circuit of supervisory relay 17 is opened and the saidv relay, upon becoming deenergized, removes the shunt from around the supervisory lamp L, whereupon the said lamp becomes lighted.

When the receiver is replaced at the substation A, the circuitof back bridge relay 77 is opened and the said relay, upon deenergizing, reverses the incoming trunk con-,

ductors back to normal, whereupon polarized relay 32 in the circuit 0 responds by re tracting itsarmature 39, thereby opening the circuit of relay 33. Upon deenergizing, relay 33 removes the shunt from around the upper portion of the high wound relay 31 at armature 40, whereupon the marginally adjusted-supervisory relay 18 in the cord circuit O deenergizes, therebyirenioving the shunt from around supervisory lamp L and allowing it to become lighted. v

The A operator, upon noting thelightcd condition of the lamps L and L knows that the conversation is completed and that the calling and called subscribers have replaced their receivers and accordingly, she

pulls down the connection. l/Vhen the plug P is removed from the jack J, cut-off relay 14, upon deenergizing, connects up line relay 13 again and the supervisory lamp L in the cord circuit 0 becomes extinguished.

When the plug P is removedfrom the jack J sleeve relay 21, upon deenergizing, opens the circuit of the busy lamps L and L whereupon V the said lamps become extinguished; As a further result of the removal of the plug P from the jack J the super- I visory lamp L in the cord circuit 0 becomes extinguished. As a still furtherresult of the removal of the plug P from the jack J the circuit of supervisory relay 31 in. the

trunk circuit O is opened and the said" relay, upon deenergizing, opens the locking circuit of connecting relay 36 at armature'37 -Connecting relay 36, upon deenergizing, opens the bridge across conductors 66 and 67 at armatures 47 and 49, whereupon theautoinatic switchesare restored to normal position in the usual manner. As a'further result of the deenergization of relay 31,-it

closes a circuit for relay 35 at armature 37, which circuit includes the working contact of armature 43 and said armatura- Upon energizing, relay 35 closes a locking circuit for itself at armature 45 and prepares aflash recall circuit for the lamp L at armature 46. energization of relay 31, it closes the circuit of lamp L at armature 38, whereupon the said lamp L? becomes lighted. Upon noting the lighted condition otthe lamp L the B operator withdraws the plug P from the jack J thereby removing the ground potential from sleeve conductor 69, where-v upon the lamp L becomes extinguished and the relays 34 and 35 deenergize. I if we assume now that the operator, being otherwiseengaged, leaves the plug P? in the jack J andthat the trunkline comprising conductors 22 and 23 is connected within the manual exchangein the usual manner, a cir cult is closed for relay 31 of the 'operators,

trunk circuit 0. Upon energizing, relay 31 disconnects the lamp L from direct ground ing contact and the interrupter I. The interrupter 1 alternately opens and closes the circuit of the lampL causing it to flash -on and off, thereby attracting the attention of-the operator immediately and informing her that another call has come-in overthe trunk comprising conductors 22. and, 23. Upon noting that the lamp L is flashing intermittently, the operatorthrows her key K As a still further result of the de-- to listening position, thereby connecting up.

the conductors of her head set at springs 61' and 62'. As a furtherresult of the operation of the key K, the lockiiig circuit of relays i 34 and35 is opened at spring 60. Relay 35,

upon deenergizing, opens still another point,

in its locking circuit at armature 45 and at armature 46 disconnects the lamp L from i the interrupter I, whereupon the said lamp.

ceases to, flash. Relay 34, upon deenergi'zing, opens still another point in its'locking circuit and prepares a circuitior supers visory lamp L at armature 44. The opera- I tor now converses with the calling subscriber in the usual manner and, after having learned the number of the desired subscriber,

throws the key K to the opposite or calling position, whereupon the supervisory lamp L", becomes lighted and the operations incident to thecalling of the desired number;

take place in the previously described manner. i

not able to hear each other distinctly. As-

suming now that the subscriber at substa tion A discovers that he cannot hear plainly enough and that the difficulty is due to a defect in the A operators cord circuit, he

' works his switch hook up'and down slowly,

thereby causing the supervisorylamp L to flash. The operator, upon noting that the lamp L is flashing, throws the key K to listening position and converses with the subscriber. After finding outthe trouble,

the A operator changes the cord circuit O'for another, whereupon the subscribers may converse in the usual manner. Itwill be remembered that according to the prer vious explanation the automaticswitches are released when the A operator takes the connection down, which she does in'effect when she, changes cord circuits. The con nection' is not released in the present instance, however, for the reason that the called subscriber'has not yet replaced his receiver and consequently relay 33 of the trunkcircuit O is operated and the connecting relay 36 is locked up to the sleeve conductor 69 of. the plug P by way of the working contact of armature 41 and said armature. As a result, the momentary deenergization of supervisory relay 31, which occurs when the A operator changes cord circuit, does not cause the deener ization of connectingrelay 36 and the connection is .held up.

"Assuming now that the subscriber at sub- 'stationA has left his receiver off the hook and, that the subscriber at substation A has replaced his receiver, and that the A open ator, after waiting areasonable length of time forthe called subscriberto replace the receiver, and possibly after having failed in an attempt to converse with him, pulls down the connection, whereupon the disconnect,

lamp Ii in the trunk circuit 0" is lighted in the usual'mannerr The B operator new pulls down .the connection, whereupon the lamp L" becomes extinguished and the con- It sometimes happens that, after a con nection is completed, the two subscribers are however, that before the own the operating her calling device, so as to determine whether or not anyof the automatic switches are operated. In case they are not, the conductors 66 and 67 extend to the windings of line relay of the selector D and the operator hears a distinctive tone which is produced by the tone machine T. But in the present case, since the conductors are disconnected from thewindings of line relay 75 of the selector D and'are extended to the windings of line relay 78 of the connector H, the operator not hearing the tone knows that a connection is partly or completely set up, and in order to release the automatic switches,.she operates the release' button B, thereby opening the bridge across tho conductors66 and 67 at the contacts 68, whereupon the automatic switches are re stored to normal position in the usual manner; I I

sci

'-When the operator releases the button B,

the contacts 68 close the bridge again'and as a result the-line and release relays 7 5 and 76 of the selector D are energized, thereby preparing the switch for operation in the usual manner. .The operator now completes the connection in the hcreinbefore de scribed manner. I

The various features of the invention, havingbeen described and explained, will now be pointed out in the appended claims.

I claim v 1. In a telephone system, means'for connectinga calling line in one exchange with a called line in a second exchange, said means including a trunk line terminating at an A position in'lthe first exchangeandat a B- position in the second exchange," a signal lamp at the B position, means for lighting said lamp when the A operator pulls down the connection in order to give the B. operator a disconnect signal, and means for, flashing said lamp in case the A operator plugs into said trunk thereafter before the connection is pulled down at the B position. y r y 2. In a telephone system, a n'ianual exchange including an A- position, an automatic exchange including a B position, means for connecting a manual calling line with an aititomatic called line, said means including a trunk extending between said positions and a series of automatic switches directively controlled from the B position, a I

the A operator plugs into the trunk again before the B operator has pulled down the connection. I

3. In a telephone system, a trunk line extendingfrom an A'position in a manual exchange to a B position in an automatic exchange, means lncludlng said trunk lines and aseries of automatic switches for connecting a calling manual line with a called automatic line, and a control circuit for said switches completed initially by the B operator, and controlled jointly bythe A operator and by the called subscriber for preventingthe release of said switches. V

4:, In a telephone system, manualancl auto matic exchanges and an interconnecting trunk line, A and B positions'in the said exchanges in which said trunk line terminates, a cord circuit at the A position for connecting a calling line with said trunk line, a local trunk line extending from the B position to an automatic switch, means for connecting said local trunk line with the inter-office trunk line, a key associated with thelocal trunk, a relay responsive-to the operation of said key to 'closea bridge across said local trunk line to complete a control circuit for said switch, a second relay controlled over said inter-otfice trunk'line to close a locking circuit for said first relay, means for operating said switch and other switches to completethe connection to a called line, 'a third relay responsive only while the receiver is off at the' called station to close another locking circuit for said first relay, and release means for said switches responsive when said bridge is opened by the deenergization of said first relay.

5. In a telephone system, a plurality of subscribers stations, lines accessible to all of said stations extending to a manual switchboard, a link circuit at said switchboard, manually controlled means at said switchboardvfor completing a connection from any calling subscribers station by way of one of said'lines to said link circuit, a signal individual to said link circuit, means responsive to the termination of a call by the calling party for preparing said signal for operation, and means responsive to a new call over the line last used before the connection has been broken down at said switchboard for operating said signal.

6. In a telephone system, lines extending to a manual switchboard, a link circuit at said switchboard, means including a cord circuit for extending a call to a line, manually controlled means at said switchboard for completing a connection from any calling one of said lines to sald link clrcult, a signal,

,for setting up a battery means individual to said link circuit responsive to the termination of a call by the calling party for preparing said signal for operation, and means responsive to a. newcall over the linelast used before the connection between theline and associated linkcircuit has been broken down'at said switchboard for operating said signal y 7. In a telephonesystem, a pluralityof lines extending to a manual switchboard, a link circuit ter'mlnatlng 1n anautomatic switch, means for setting up a telephone con-' nection including any one of said lines, said link circuit and said automatic switch,means individual to each line for informing the operator of initial calls, a signallingfldevice individual to said link circuit, means for preparing said device for to the calling party terminating the initial call, and means for operating said device to inform the operator of a second callvover the connected line. v

8.--In a common battery telephone sys;

tern, a plurality of subscribers stationsya plurality of lines accessible toall of said stations extending'to a manual switchboard,

a call-signal device individual to each line 7 from a subscribers.

and responsive to aca-ll station over the associated line, a linkciP cuit at said switchboard for completing a telephone connection including any one of saidlines, and a recall signal device in said link circuit responsive to the current flow set up from .the common battery when a new call comes in over a linebefore a connection previously set up over the same line through said link circuit has been broken down.

9. In a commonbattery telephone system, 7 plurality of lines terminating thereat, a cord circuit, a linktelephone conned said lines andsaid cord circuit, means for breakingdownsaid a manual switchboard, a

circuit for; completing a t1on includmg any one of operation responsive connection at the termination of said conversation, means for bringing in a new call on the connected'line and link circuit and current flow there'- over prior to the breaking'down-ofa previous connection of-said line and link circuit,

and current-flow detecting means in said,

link circuit common to all said lines'for ap prising the operator of the new call.

10. In a telephone system, a line extendlng to a manual switchboard, directively operated manually controlledv automatic switching means whereby the operator at said switchboard can set up a telephone connection including said line, a signal lamp at said switchboard, a recall circuit for said signal lamp, a relay at said switchboard maintained operated as long as the original call remains on said line, a second relay operated responsive to the restoration of the first relay when the original call is cleared out to prepare said recall circuit,'whereby said recall circuit is completed upon the reopcration of the first-named relay when a second call comes in over said line prior to the taking down of the connection at the manual switchboard. '7

. .11. In a' telephone system, a link circuit, means 'for extending a connection from a calling line to said link circuit, a train of automatic switches for further extending the connection from said link circuit to a called line, means in said link circuit controlled 7 over the calling line by current flow thereover. for maintaining said automatic switching mechanism operated, whereby said auto- 7 responsive to m'atic switching mechanism may be released the stopplng ot the current flow over the calling line by the calling party, and means in said link circuit controlled by the responded state on the called I, up a telephone connection from a calling line to a called line, means for maintaining the. automatic switches operated subject to ill.

the 'maintenance of a current flow in the" callingline, and means controlled through said switches by the setting up of a current flow over the called line when the called. subscriber responds for rendering the releasing means of said automatic switches non-responsive to the cessation of current flow, in the calling line, while maintaining direct current flow during conversation in every portion of the talking circuit extending between the calling and called'lines,

' 13. In a telephone system, an A posi-f tion, a B position, a trunk connecting the v two, a signal at the A position for in dieating the busy conditionof the end ot the trunk that terminates at the A position regardless of the busy or idle condition of the other end of the trunk, a signal at the Bpositi0n and means for operating the signal responsive to the seizure of the trunk at the A position if the trunk is idle at both positions, a second signal at theB position,- and meansfor operating the last mentioned signal uponithe seizure at the A position of the trunk if the trunk is idle at the A position but busy at the B P si i nv Y Y 4; In a telephone system, an A position, affB position a trunk connecting the two, a si nal atthe A position for indicating the usy condition of the end of the trunk thag tg minates at the A position regardless f the busy onidle conditio of the. other end of the trunk, a signal at the B 'positiclla and means for operating the last mentioned signal upon the seizure at the A pos tion of the trunk it the trunk is idle at the A,

position but busy at the B position, and means at the B position for reestablishing the initial condition. of the last'mentioned. signal without changing the busy condition of the trunk. a y

15, In a telephone system, first and second operators positions, an automatic switch, a, line, a trunkconnectlng the. two positions,

means including the automatic switch for setting up aconnection from the trunk to the line, a signal at the, second operators position, and means responsive to the establishment of a connection to the trunk at the first position during the existence, at a second position, of a connection over the automatic switch for operatingthe signal.

16'. In a telephone system, first and second operators positions, an automatic switch, a line, a trunk connecting thetwo positions, means. including the automatic switch for settingup a connection from the trunk to the line, a signal'at the second operators position, and means responsive tothe establishment of a connection tothe trunk at the first position during the existence of a coni A nection over the automatic switch at the. second position for operating the signal, and means at the second position for-reestablishing the initial condition oft-he signal,

17. In a telephone system, first and second operators positions, an automatic switch, a

line, trunk connecting thevtwo positions,

means including the automatic switch for setting up a connection from'the trunk to ing theinitia-l condition of the signalindev pendent of the release otthe switch.

18. In a telephone system, two operators V positions, an automatic switch, a line, means including the automatic switch for extendin I a call to the line, means for releasing sa dautomatic switch, means underthe con trol of one of said"operators for operating the releasing means, means under the control. of the last mentioned operator for trans ferring the control of the releasing means. to the other operator, and means efiiective after the call hasbeen answered for rendering the control by said other operator subject to the control by the called party.

19.'In a telephone system, two operators" positions, an automatic switch, a line, means including the automatic switch for exte 'iding a call to the line, means for releasing said 'theQline, a signalat the second operators position, means responsive to thccstablishautomatic switch, means under the control of oneof said operators for operating the releasing means independent of the called party means under the control of the last mentioned operator for transferring the con trol of the releasing means to the other op erator, and means effective after the call has CLARENCE E. LOMAX. 

